This invention relates to an electrical heating element and in particular to an electrical heating foil element consisting of a resistance strip element laminated between two sheets of insulation material, where at least one of the insulation sheets extends beyond the heated area at least on one side, so that on this side there is obtained an insulated fastening area (nailing zone) which can be mechanically reinforced.
Such an electrical heating element is known from Norwegian Pat. No. 147,975 to H. A. Bergersen.
When such a heating element is to be installed within a floor structure, it is usually arranged on the top of an insulation mat with a free air space having a specified minimum height (specified according to safety conditions) between the element and the floor boards. The heating elements must be arranged according to given specifications.
However, when the floor building process starts with mounting of the floor boards to the top of the joists, some practical problems occur because it is difficult to arrange the insulation mats with the thin and flexible heating elements on top in the correct and specified position from beneath, between the joists. And due to safety requirements on building sites, this floor building method, starting from above, is now common practice.
Normally there are first fastened some bridging supports from joist to joist. These bridging supports are usually made of cardboard or millboard ribbons which are nailed to the side faces of the joists at specified positions. The heating elements are then placed on the top of the bridging supports and finally the insulating mats are fastened and supported from beneath.
This procedure is rather complicated, since the exact position of each bridging support has to be measured out and marked. The bridging supports also represent increased costs and storage capacity.